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From: Pavel Begunkov <[email protected]>
To: [email protected]
Cc: Jens Axboe <[email protected]>, [email protected]
Subject: [PATCH for-6.1 1/4] io_uring: update res mask in io_poll_check_events
Date: Thu, 17 Nov 2022 18:40:14 +0000	[thread overview]
Message-ID: <2dac97e8f691231049cb259c4ae57e79e40b537c.1668710222.git.asml.silence@gmail.com> (raw)
In-Reply-To: <[email protected]>

When io_poll_check_events() collides with someone attempting to queue a
task work, it'll spin for one more time. However, it'll continue to use
the mask from the first iteration instead of updating it. For example,
if the first wake up was a EPOLLIN and the second EPOLLOUT, the
userspace will not get EPOLLOUT in time.

Clear the mask for all subsequent iterations to force vfs_poll().

Cc: [email protected]
Fixes: aa43477b04025 ("io_uring: poll rework")
Signed-off-by: Pavel Begunkov <[email protected]>
---
 io_uring/poll.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/io_uring/poll.c b/io_uring/poll.c
index f500506984ec..90920abf91ff 100644
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -258,6 +258,9 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
 				return ret;
 		}
 
+		/* force the next iteration to vfs_poll() */
+		req->cqe.res = 0;
+
 		/*
 		 * Release all references, retry if someone tried to restart
 		 * task_work while we were executing it.
-- 
2.38.1


  reply	other threads:[~2022-11-17 18:40 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-17 18:40 [PATCH for-6.1 0/4] minor poll fixes Pavel Begunkov
2022-11-17 18:40 ` Pavel Begunkov [this message]
2022-11-17 20:31   ` [PATCH for-6.1 1/4] io_uring: update res mask in io_poll_check_events Gabriel Krisman Bertazi
2022-11-17 18:40 ` [PATCH for-6.1 2/4] io_uring: fix tw losing poll events Pavel Begunkov
2022-11-17 18:40 ` [PATCH for-6.1 3/4] io_uring: fix multishot accept request leaks Pavel Begunkov
2022-11-17 18:40 ` [PATCH for-6.1 4/4] io_uring: fix multishot recv " Pavel Begunkov
2022-11-17 19:46 ` [PATCH for-6.1 0/4] minor poll fixes Jens Axboe

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